Nothing has changed in the last 5 years. Although we can say "such," it's more common to hear "so." They mean the same thing. The word "fun" can be both a noun or an adjective. In this particular scenario, it's being used as an adjective. Words like "is" and "are" are classified as verbs. Specifically, they are called linking verbs. There are 23 linking verbs in English. They are as follows: is, am, are, was, were, be, being, been, has, have, had, do, does, did, shall, will, should, would, may, might, must, can, could.